Inner tube insert



FIG. 1 is a top perspective view of the inner tube insert showing my new design, the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 2 is a side elevational view thereof, the opposite side view being a mirror image of that shown; and,

FIG. 3 is a top plan view thereof, the bottom view being the same except that there are no handles. 

The ornamental design for a inner tube insert, as shown and described. 